Scott 350R Service Manual

Page 1

Scott 350R/RL

ADJUSTMENT

Equipment Required
Audio signal generator.

Level meter.
DC voltmeter.
Oscilloscope.

Digital frequency counter, 0 - 100 kHz.
FM multiplex signal generator.

Circuit tester.

Distortion analyzer.

FM RF Tracking

7 Dummy
El Ant. 300 ohm Tape
0 O én t. Rec 0 c
" j 0 or
FM Signal Genera tar Level Meter Oscilloscope
l-dp-O o- _
o

1) Apply 90 MHz, 1 kHz and 100% modulated. 65 dBf signal
with 75 kHz deviation to the FM antenna terminal.

2) Tune the unit to 90 MHz.

3) Observe the oscilloscope connected to the Tape Rec output
terminal for symmetrical sine wave. If failed. adjust T4.

4) Adjust T1, T2 and T3 for maximum level meter reading
(connected in parallel with the oscilloscope).

FM IF Amplifier

Distortion Analyzer I Used in IF Distortion)

5) Readjust the signal generator for 106 MHz, and retune unit.

6) Repeat step 3), if failed, adjust the trimming capacitor,
CTf.

7) Adjust the trimming capacitors. CTa, CTc, and CM.

8) Repeat above steps until no further improvement is ob-
tained.

78446, etc. 0'00:
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TOP/n 13.. ' = . '
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. :> I
O o 8: 3 Turn COI/ : 470k I :
° ° To Chassis l "hm - l _4'° o
Sweep Generator T3 Ground Oscilloscope
1) Mute the FM local oscillator by shorting CV6.
2) Connect oscilloscope to pin #13 of [CL
3) Apply 10.7 MHz signal from the sweep generator to 963
in the manner as shown above.
4) Adjust T5 for correct figure as provided to the right. It
may be necessary to increase or decrease the sweep gener-
ator output for adjustment convenience. cam $05,292: $23,233,

[F Distortion

1) Apply 98 MHZ. 1 kHz and 100% modulated, 65 dBf signal
to the unit.

2) Adjust T7 for minimum distortion on the distortion ana-
lyzer connected to the Tape/Rec output terminal.

Page 2

Tuning Meter

1) Remove signal generator output from the unit.
2) Adjust T6 for exact center reading on the FM Center Tun-

Signal Strength Meter [FM]

1) Apply 98 MHz, 90 dBf signal to the unit.
2) Tune the unit for 98 MHz.

Mute Circuit
1) Apply 98 MHz, 20 dBf signal to the unit.

2) Tune the unit (with the Mute switch in the Off position).
3) Set the Mute switch to the On position.

Pilot Signal (76 kHz)

1) Apply 98 MHZ, 65 (Sf signal to the unit With no modu-
lation.

2) Adjust RVS for 76 kHz reading on the frequency counter

Stereo Separation

1) Apply 98 MHz. 65 dBf left channel signal to the unit modu»
lated with 1 kHZ, 9% pilot signal of 6.75 kHz deviation.

2) Connect a digital voltmeter to the right channel Tape/Rec
output terminal.

3) Adjust RV2 for minimum leakage (minimum level) on the
voltmeter.

AM IF Amplifier

1) Apply 455 kHz sweep generator output to the unit AM
antenna terminal.

2) Connect scope to the pin number 12 of lCS.

5) Adjust T8 to obtain maximum and symmetrical display as
shown to the right.

AM Tracking

ing meter.

3) Adjust RVl for 90% reading on the signal strength meter.

4) Rotate RV9 to the point where the signal is muted. Do not
rotate too far.

connected between TP and chassis ground. A deviation of
1200 Hz is acceptable.

4) Apply 98 MHz, 65 dBf right channel signal to the unit
modulated same as step 1).

5) Move digital voltmeter to the left channel Tape/Ree output
terminal.

6) Check for minimum and equal leakage on both channels.

Tape/
Rec out

OO

AM Signal Generator Radiation
Loan

1) Apply 600 kHz signal. 30% modulated with 1 kHz to the

0
Level Meter Oscilloscope

AM bar antenna. See test setup figure (Distance between